Measurements by the inventor's co-workers on IR-CCD imagers of the focal-plane-array (FPA) type, which employ platinum-silicide-silicon Schottky barrier diodes as photosensors, have proven that imager sensitivity to IR is increased by applying an IR bias to the imager prior to the transfer of charge samples from the SBD's to the CCD portion of the imager. Arrangements for applying such IR bias in a working camera tend to be impractical, however.
The IR bias generates charge carriers by photoconversion that fill surface traps and provide what is essentially the equivalent of a fat zero bias charge for the charge transfer process that removes charge packets accumulated in the photodetectors. These charge packets are then conveyed by charge-coupled-device shift registers to the imager output. It is proposed to introduce bias charges into the photodetector SBD's by charge transfer, rather than by photoconversion.